1. Field of the Invention
The present invention relates to a driving force transmission device provided between the units in a corrugated cardboard box making machine.
2. Description of Related Art
In a corrugated cardboard box making machine, a feed unit, a printing unit and a slotting unit are connected in alignment and they are driven in a state of synchronization with a driving source.
Maintenance procedures such as exchange and cleaning of printing plates in the printing unit and exchange of slotting knives in the slotting unit are frequently carried out. In order to readily carry out such procedures, each unit is arranged to move on a box making line and to separate from one another.
FIG. 12 shows a driving system in a feed unit 51, a printing unit 52 and a slotting unit 53 of a conventional corrugated cardboard box making machine. Each one of the units 51,52,53 is provided with a gear transmission 51a,52a,53a comprised of a spur gear train.
The feed unit 51 is provided with a driving motor to rotate the gear transmission 51a for driving a movable member such as transport mechanism in the feed unit 51. A driving force is transmitted from a gear 51p in the feed unit 51 to a gear 52p in the printing unit 2 to rotate the gear transmission 52a in the printing unit 52 thereby driving movable members such as a printing cylinder in the printing unit 52.
A driving force is transmitted from a gear 52q in the printing unit 2 to a gear 53q in the slotting unit 53 to rotate the gear transmission 53a in the slotting unit 53 thereby driving movable members such as a slotter shaft in the slotting unit 53. In such a manner, each one of the gear transmissions 51a,52a,53a is simultaneously rotated, and printing drum, slotter shaft and the like are operated at a predetermined timing.
The procedures of changing printing plates, slotting knives, etc. are carried out so that each unit 51,52,53 is separated, and during the procedures, the printing cylinder and the slotter shaft are rotated independently. Accordingly, after the procedures, if each unit 51,52,53 is again connected without making any arrangement, the operation timing of each unit 51,52,53 is disturbed. In other words, when the box making machine is operated after each unit is connected again, the printing position does not coincide with the position initially set in the printing unit 52, while the slotting position does not coincide with the position initially set in the slotting unit 53 since the state of engagement of gears at the positions P, Q shown in FIG. 12 is changed from that of the original state. In order avoid these inconveniences, each unit 51,52,53 has to be reconnected so as to coincide with the original state by engaging the gears 51p,52p,52q and 53q positioned at P, Q shown in FIG. 12.
Heretofore, it has been practiced to put a mark on the gears 51p,52p which engage with each other at the position shown by P to indicate initially set positions before each unit 51,52,53 is separated, and likewise, the gears 52q,53q which engage with each other at the position shown by Q were marked to indicate initially set positions in order to solve the above-mentioned problems. According to this method, when each unit 51,52,53 is reconnected after some necessary maintenance procedures in a manner to engage the marks coincide with the gears 51p,52p,52q,53q, the box making machine after it is reconnected can be operated with proper operation timing.
However, in order to have the marks of the gears 51p,52p,52q,53q coincide with each other, the printing drum in the printing unit 2 and the gear transmission 52a, for instance, have to be rotated manually by overcoming the inertia the printing drum and the gear transmission possess which requires operator a great effort of the in the conventional method. At the same time, it requires the operator to pay strict attention to the work of marking before each unit 51,52,53 is separated and also to the work of causing the marks coincide with each other when the units are reconnected. In addition to the problems inherent in the conventional method as above-mentioned, there is also a problem that when each unit 51,52,53 is separated, the oil on the gears 52p,53q drop to the nearby floor and stain the floor since the gears 52p,53q are extruded outwardly from the connected surfaces of the units.
In order to cope with the problem, there is a device disclosed in the Japanese Patent Application TOKKAI SHO 62-191131. In the device, a driving shaft is provided on each one of units for driving movable members of the unit, and the driving shafts are arranged movable toward and away from each unit to be connected by a coupling. However, according to this prior art, there was a difficulty in making smooth connection between the driving shafts since frictional resistance is too large when they are connected. Moreover, the durability of the coupling is not sufficient and it is unable to provide the arrangement for practical use.